Effects of air humidity and soil moisture on secondary metabolites in the leaves and roots of Betula pendula of different competitive status.

Plant secondary metabolites (PSMs) defend plants against abiotic stresses, including those caused by climate change and against biotic stresses, such as herbivory and competition. There is a trade-off between allocating available carbon to growth and defence in stressful environments. However, our knowledge about trade-off is limited, especially when abiotic and biotic stresses co-occur.